Charles e



(No Model.) 2 Sheets-Shet 1;

o E. SGRIBNER. MULTIPLE SWITGHBOARD SYSTEM FOR TELEPHONE EXCHANGES.

No. 488,038. Patented Dec.. 18, 1892.

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MULTIPLE SWITGHBOARD SYSTEM FOR-TELEPHONE EXGHANGES. No. 488,038. I Patented Dec. 13, 1892.

WITNESSES INVENTOR /5 K462, Charleg EScrzZner. flw fim; BYWWW ATTIYS:

- 'jrp-l: NORRIS PETERS co PHOTQLITNCL. WASHINGTON n c Unrrno TATES' ATENT Charon;

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR T THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

MULTIPLE-SWITCHBOARD SYSTEM FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 488,038, dated December 13, 1892.

Application filed April 18, 1892. Serial No. 429,664. (No model.)

To all whom it may concern.-

Be it known that 1, CHARLES E. SoRIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Multiple Switchboard Systems forTelephone-Exchanges, (Case No. 302,) of which the following is a full, clear, concise, and exact description,reference being had to [O the accompanying drawings, forming a part of this specification.

My invention relates to multiple-switchboard systems in which the individual annunciatorof atelephone-line remains permanently I5 connected to the line-circuit while the line is in use. Its object is to provide a system of this type in which the operation of the individual annunciator by signaling-currents sent subsequent to the establishment of a connection with the line may be prevented and to provide suitable means for testing at one board to determine whether a line is in use at some other switchboard or not.

It will be understood that in multiple-switchboard systems if the individual annunciators of all the lines should remain permanently connected to the line and be free to operate while the line was in use the signal for disconnection or similar signals sent over the line during its use would operate the individual annnnciators of both lines, thus calling the attention of two operators at different boards to the line-circuit and causing confusion. Moreover, in multiple-switchboard exchange systems in which a spring-jack for each line is placed upon each section of multiple switchboard it becomes necessary for the operator at each section of switchboard to be enabled to determine at her own board whether any particular line is in use through a connection established at some other switchboard or not. To this end it is customary to provide a testing-contact upon each spring-jack of the line, all the testing-contacts of one line being connected together, and means for altering the electrical condition as to their difference of potential from the earth through the establishment of connection with the line. In order to economize space, the test-rings or testcontacts form the terminal contacts of one side of the line-circuit, and being thus permanently connected with the line-circuit have received induced static charges or potential differences from the earth by inductive and other influences external tothe exchangeand have thus given false signals when tested. In my invention is provided an individual annunciator having its ele'ctro-magnet polarized so as to attract its armature in response to' currents of a particulardirection,having one of its coil-terminals connected to the line-circuit and the other to earth and in connection with the cord-circuit or connecting-circuit at the exchange a battery of such polarity that when the cord-circuit is employed in establishing connection with the line the battery will find circuit through the polarized individual annunciator of that line and will tend to retain the individual annunciator unresponsive, the strength of the battery being such as to prevent its operation by any ordinary signaling-current. I employspring-jacks of the usual construction-that is, having two contact-pieces, a line-spring and a test-ring, the

test-rings being connected together; but in my system the test-rings are normally disconnected from the line-circuit and are connected to the corresponding side thereof onlyduring the existence of a connection with theline. This connection between the line -circuit and So the test-rings is eifected by an electro-magnetic device adapted to be energized by a battery in connection with the cord-circuit in a manner similar to the energization of the individual annunciator of the same line. In 8'; practice I have found it convenient to provide the individual annunciator with contactpoints, one connected with the test-rings and the other with the corresponding side of the line-circuit, arranged in such relation as to be closed together when the annunciator is energized by the battery in connection with the cord-circuit. The normally-insulated testrings are thus during connection with a line electrically crossed with any source of electricity, as the retaining-battery in the cordcircuit, which may be connected to the line, and therefore when tested, for example, with a test-plug connected through an appropriate responsive device to earth will produce a re- 10o sponse, thus indicating. to the operator test-' ing that the line is in use. I have found a suitable individual annunciator for this purpose to be a polarized annunciator of ordinary character having its armature so weighted or adjusted as to hang in an intermediate or neutral position between two electro-magnets and to be attracted by one or the other in response to currents in proper direction to energize one or the other coil. In connection with the armature is provided a catch, which in its neutral position engages with a shutter to prevent it from falling and with an arm carrying a movable contact-piece and holding it separated from this corresponding contactanvil. When a calling-signal is sent from the sub-station over the line, the signaling-current being of proper direction, the armature is attracted to one of the electro-magnets and releases the shutter, thus indicating the signal to the attending operator. nection has been established to the line by means of a cord-circuit having a battery connected to it, the current from the battery finds circuit from the annunciator, as described, in a direction to cause the armature to be attracted to the other electro-magnet, thus re.- taining the shutter inoperative, and at the same time closing the contact-pieces together, thus connecting the normally-open side of the line-circuit to the test-rings of its springjacks.

My invention is illustrated in the accompanying drawings, Sheet 1 and Sheet 2.

Figures 1, 2, and 3, Sheet 1, represent a polarized individual annunciator such as that described. Fig. 1 is a plan thereof. Fig. 2 is a side elevation thereof, showing a portion of the frame supporting the armature broken away, so as to disclose the armature and the electro-magnet poles. Fig. 3 is a front elevation of the annunciator. Fig. 4, Sheet 2, isa diagrammatic representation of the exchange organized in accordance with my invention, comprising two sub-stations connected to the exchange by metallic circuits, each line-circuit being provided with spring-j ack switches upon two sections of multiple switchboard and with an individual annunciator at one of the switchboards. A cord-circuitis shown at each of the switchboards, that at one of the boards being in position of testing one of the lines to determine whether it is alreadyin use or not.

Referring to Sheet 1, a, b are two electromagnets having their free poles presented toward each other. Magnets a and bare joined at their other ends by bar 0 of steel, which is permanently polarized. The bar 0 thus serves to impart a permanent electro-magnet polarity to the cores of magnets a and b in a certain direction, and at the same time to complete their magnetic circuit. Two plates or bars 01 d of non-magnetic material are secured at their extremities to magnet c, carrying at their central portions upwardly-pro- When the con jecting posts or extensions e 6, provided with adjustable trunnions 6 e An armature f of soft iron is pivoted at its upper edge upon the trunnions 6 e so as to be suspended vertically midway between the presented poles of the electro-magnets a and b and to be free to swing toward the one or the other, according to which is most strongly energized. The armature f preferably extends to within a slight distance of the heel piece or bar 0, so as to nearly complete the magnetic circuit of that coil toward. which it is more strongly attracted. An arm 9 is rigidly secured at right angles to the armature f, extending on both sides thereof. A plate h is secured to one end of the electro-magnet system and carries upon its front a number-plate lo and a shutter or shield is, hinged at its lower edge and of such size and shape as to conceal the number-plate when in the position shown, as in the usual individual annunciator. The shutter 70' is normally retained in the position shown by a catch g upon a corresponding extremity of the arm g, engaging with the upper edge of the shutter. The catch is of such length as to allow to the arm g a slight downward movement in excess of that required to retain the shutter. At the other extremity of the bar 0 is provided a contact-anvil Z, rigidly secured to the bar 0, but insulated therefrom by an interposed hard rubber plate. A contactiece Z is rovide'd u on the corres ondin P P P P e extremity of the bar g, adapted to be closed against the contact-anvil I when that end of the arm 9 is raised to a sufficient amount.

The normal position of the armature is as shown in Fig. 2, the armature being in itsintermediate or neutral position, the ,contactpoints being open or separated,and the shutter being in a position to conceal the number upon the plate. When a current of suitable direction is sent through the coils a b of the annunciator, the armature fis attracted toward the coil at, raising the catch 9 out of engagement with the shutter 70' and allowing the latter to fall, disclosing the number or name upon the plate 70 to the attending operator. When current is sent in the opposite direction through the coils a b, the armature f is attracted to the coil 1), closing the contact-points Z Z while still retaining the shutter 70'.

Referring now to Sheet 2, Fig. 4, I will describe the exchange system therein represented. The apparatus at the exchange may be of the ordinary character, comprising a magneto-generator m, adapted to send alternating currents, and a signal-bell m and a telephone-receiver m and transmitter m in different branches from one side it of the line-circuit, and a gravity-switch m connected with the other branch n of the linecircuit and adapted to connect the signaling apparatus or a telephone apparatus alternately into line-circuit, according to the position of the switch-lever. An earth connection' is attached to thatside of the branch containing the generator and signal bell, which is adapted to be connected with the side at of the line-circuit, in order that signaling-currents maybe sent orreceived either through the metallic circuit n n or the grounded circuit made up of side it of the circuit and the earth. The lines at 71' extend to the exchange where the line n is connected to the line-springs 0 of two spring-jacks p 10' upon two sections of switchboard q q. The spring-jacks p 10' have, in addition to the line-springs 0, test-rings 0, as usual. An ex tension from the side n, of the line-circuit includes coils a and b of the individual annune ciator 7* upon the switchboard q. The testrings 0' of the different jacks p p are connected together by a conductor and to the arm g of the individual annunciator. The side n of the line is connected with the contact-anvil Z of the annunciator. The connecting outfits at the different switchboards are of the usual character. Each comprises a pair of loop-plugs s s, the like contactpieces of the two plugs of a pair being connected by conductors tt'. Ringing-keysuu are included in the cord-circuit, each arranged to disconnect the sleeve of one of the loop-plugs from that of the other and to connect the poles o 'u of a calling-generator '0 into circuit with its particular plug. Alistening-key w is provided, having its contactsprings connected to the conductors t t of the cord-circuit and having its contact-points connected with the terminals of the operators telephoneset w. A clearing-out annunciator a: is permanently included in a bridge connection between the conductors t t. A battery y, grounded at one pole, has its other pole connected to the conductor t, connecting the tips of the different connectingplugs.

In the operation of the system a subscriber wishing to communicate with another subscriber connected with the same exchange r0- tates the calling-generator m, the switch'm being in its lowest position. The signalingcurrent finds circuit from one pole of the generator m to earth through the signal-bell and from the other pole over line-wire 'n to the exchange and therethrough the coils b anda of the individual annunciator 1' and thence to earth. The signaling-current being of alternating character, polarized annunciator r is operated, attracting the attention of the operator at board q. The operator at this board then inserts one plug, as s, of a pair into the jack p of that line at her board and restores the shutter of the individual annunciator to its normal position. The battery y is then provided with a circuit through the retardation-coil to the cord-strand tand thence to the tip of plug 8, thence to the line-spring 0 of jack 1), thence through the individual annunciatora" to earth, energizing the annunciator in such manner that the armature thereof is attracted to the coil 19, causing the catch 9 to enter into further engagement with the shutter and closing the contact-point Z upon the contact-anvil Z, thereby connecting the side it of the line-circuit to the conductor connecting with the test-rings 0' of the spring-jacks of that line. depresses the plunger of her listening-key w, connecting her telephone-set w in a loop-cir- The operator at board q then.

cuit with sub-station 1, which may be traced;

as follows: From the sub-station over line at to line-spring o of jack p, thence to the tip of plug .9, thence by conductor 2? to listening-key w and the telephone-set w, thence to the conductor 15, through the ringing-key 'u, to the sleeve of plug 3, thence to the test-ring 0 of jack 19', to the arm g of the annunciator a", to

the contacts Z Z, and thence by line-wire'n to sub-station. The operator and the subscriber are thus provided'with a metallic circuit connecting them. The operator having received the order from subscriber at station lsay for a connection with station 2proceeds to test that spring-jack at her board of the line called for to determine whether the line is already in use or not. This she does in the well-known wayby applying the tip of the other plug 3' of the pair to the test-ring of the jack p? of lines to station 2. The plug 3 of the cord-circuit at board q is shown in the'position of testing the jack p of this same line, and the process of testing may be most readily' followed in connection with that cord-circuit. If the test-ring of an unconnected line be tested in this manner, the operator makthe jack tested to'the line-wire connecting therewith at the individual annunciator, as line-wire n thence to earth if the line be a grounded line, or returning over theline-wire n to the individual annunciator, and to earth if the line be a metallic-circuit line, and a click will be produced in the receiver w at at each application of the testing-plug to the test-ring of the spring-jack. It is not necessary that the operator should receive any particular characteristic response in her telephone when she applies the tip of her testingplug to the test-ring of the spring-jack. Itis sufficient that she receive any response, since the test-rings are normally-that is, in the unconnected condition of the line wholly disconnected from the line-circuit and from the earth and will give no test-signal when tested. Suppose the operator at board g has found the lines to station 2 not in use. She

inserts the other plug 8', with which she has shown and described.

been testing, into the jack p of that line at her board. The battery y is thereby connected with the annunciator rof that line, energizing it in the proper direction to close the side of line a to the test-rings. V The two sub-stations 1 and 2 are thus looped into a con tinuous metallic circuit, which may be traced, as before, over sub-station 1 as far as conductors t 25', from which it is extended by means of plug 8' and the corresponding contact-pieces of the jackp to theline-wires n a and thence to sub-station 2. The operator then depresses the plunger of calling-key u, disconnecting one side of the cord-circuit from the connecting-plug and looping the calling-generator 11 into circuit between the contact-pieces of plug 8', thus sending current to the sub-station 2, which finds circuit through the signalbell m thereat to call the subscriber at that station. The operator, having ascertained that the'subscribers at stations 1 and 2 are actually in communication, allows the plunger of listening-key w to rise, thus disconnecting her telephone set from the cord-circuit.

.When the subscribers have completed their conversation, one of themwe will say that one at station 1-sends a signalfor disconnection to the exchange by again rotating his generator m, the telephone having been replaced upon the switch-hook m The signaling-current finds circuit over the metallic circuit n n to the cord-circuit it, thence through the clearing-outannunciator 00, which is thereby operated, indicating the disconnection-signal to the attendant. A portion of the signaling-current escapes to the earth at sub-station 1 and'at the exchange through annunciator 1'; but the annunciator is prevented from releasing its shutter by the force of the battery y.

I do not desire to limit myself to the particular arrangement of apparatus herein Many modifications of the annunciator 0" may be found equally eifective with the form shown. Moreover,in some instances it may be found desirable to provide a separate electro-magnet to operate the contact-pointsl Z to connect the line-wire n to the test-rings of the line to complete the'metallic circuit; neither do I desire 'to limit myself to the particular means described for determining at any switchboard whether the testrings of the line are connected or disconnected with the line-wire. Various forms of responsive device and various means of prod ucinga difference of potential or altering theelectrical condition of the test-rings will readily suggest themselves to those skilled in the art.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The combination, with a telephone-line circuit, of spring-jacks having contact-pieces normally disconnected from the line-circuit and an electro-magnetic device in the linecircuit, adapted when energized to connect the contact-pieces of the said spring-jacks with the line-circuit, substantially as described.

2. The combination, with a telephone-line circuit, of spring-jack switches having contact-pieces normally insulated therefrom and an electro-magnetic device included -in the line-circuit or in a branch therefrom, adapted when energized to connect the contacts of the spring-jack switches to the line-circuit, and means for energizing the said electromagnetic device, substantially as described.

3. The combination,'with a telephone-line circuit, of spring-jack switches, each having two contactpieces, one permanently connected with one side of the line-circuit and the other normally insulated, an electro-magnetic device in a grounded branch from the linecircuit, provided with contact-points adapted when actuated to connect the normally-insulated contact-pieces of the springjacks to the other side of the line-circuit, a grounded source of electricity at the exchange, and means for connecting the same to the permanently-connected contact-pieces of any spring-jack to energize the electromagnetic device to complete the connection the spring-jacks to a conductor adapted to alter the electrical condition of the said testrings, a grounded source of electricity, and means for connecting the same to the side of the line-circuit containing the said electromagnetic device when connection is established with the line, substantially as described.

5. The combination, with a telephone-line extending from a sub-station to an exchange, of spring-jacks at the exchange, connected with theline-circuit, each having two contactpieces, one of which is normally connected to the line-circuit, the remaining contact-pieces of all the jacks being connected together and normally insulated, an electro-magnetic device in a branch to earth from that side of the line-circuit which is permanently connected to the spring-jack contacts, contactpoints adapted to be actuated by the electromagnetic device when energized, connected to the normally-open side of the line-circuit and to the normally-insulated contact-pieces of the spring-jacks respectively, a connecting. plug at the exchange adapted for insertion IIO into any spring-jack provided with two contact-pieces to make contact with the different contact-points of the spring-jack, and a grounded source of electricity connected to that contact-piece which makes contact with the permanently-connected contact-piece of the spring-jack, whereby the normally-open side of the line is connected to the normallyinsulated contact-piece of the spring-jack when the connecting-plugisinserted into any spring-jack of the line, substantially as described.

6. In an individual annunciator, the comb'ination, with two permanently-polarized electro-magnets, of an armature normally rctained in an intermediate position between them, indicating mechanism adapted to be actuated by movement of such armature in one direction, and contact-points adapted to be closed by the movement of the armature in the other direction, said indicating; mechanism being at the same time prevented from operating, substantially as described.

7. The combination, with the electro-magnets a and b, of the bar 0, arranged to produce constant polarity of the electro-magnets a and b, pivoted armature f, adapted to move toward either electro-magnet a or b, but normally retained in anintermediate or neutral position, the arm g, connected with said armature, provided with a catch engaging with an indicator or shutter It and provided with a contactpoint Z, disposed to be closed upon a contactanvil Z when said armature is attracted by one of the magnets, substantially as described.

8. Thecombination, with a telephone-line extending from a sub-station to an exchange, of an annunciator at the exchange connected with the line-circuit and provided with contact-points adapted to be closed when the annunciator-magnet is energized, spring-jacks, each having two contact-pieces, one of which is permanently connected with one side of the line-circuit, the other side of the line-circuit terminating normally at one of the contactpieces upon the annunciator, the other contact-piece upon the annunciator being connected with the remaining contact-piece of each of the spring-jacks, a source of electricity, and circuit connections and means for includding the source of electricity in circuit with the individual annunciator when desired, whereby the sub-station is connected with the spring-jacks at the exchange in a metallic circuit when the annunciator is energized, substantially as described.

9. The combination, with a telephone-line extending from a sub-station to an exchange, of an individual annunciator at the exchange provided with contact-points adapted to be closed together when the electro-magnet of the annunciator is energized, spring-jack switches connected with theline-circuit at the exchange,

and normally-insulated contact-pieces upon the spring-jack switches connected with one of the contact-pieces upon the annunciator, the other contact-piece thereupon being permanently connected with a conductor adapted to alter the electrical condition of the normally-insulated contact-pieces upon the springjacks, substantially as described.v

10. The combination, with a telephone-line extending'fr'om a sub-station to an exchange, of a-polarized individual annunciator in an earth connection from one side of the linecircuit, provided with an indicator adapted to be released by movement of its armature-in one direction, two contact-points arranged to be closed by movement of the armature in the other direction, spring-jack switches, each having two contact-pieces, one of which is permanently connected to the grounded side of the line-circuit, the" other being normal-1y insulated and connected to one of the contacttact-point forming the terminal'of the normally-open side of the line-circuit, a loopplug adapted for insertion into any springjack of the line, provided with contact-pieces arranged to make contact with the corresponding contact-pieces upon the spring-jack, a

source of electricity connected with that contact-piece of the loop-plug arranged to make contact with the contact-piece ot' the jack which is permanently connected with the line, said source of electricity being of such polarity as to energize the polarized annunciator to close the said contact, and a source of electricity at the sub-station adapted to be connected to the permanently-grounded side of the line-circuit and of such polarity as to actuate the annunciat-or to operate its indicator when connected with the line-circuit,substantially as described.

11. The combination, with two telephonelines extending from two sub-stations to an exchange, each being provided with a polarized individual annunciator having an armature adapted to move in either direction, of an indicator arranged to be operated by move ment in one direction, and contact-points arranged to be closed by movement of the armature in the other direction, one of said contact-points being permanently connected to a normally-open side of its particular. line-circuit, the electro-magnets of each annunciator being included in a permanently-grounded branch from the other side of its particular line, spring-jack switches, each having two contact-pieces, one of which is connected with the grounded side of the line-circuit, the other of which is connected with the remaining contact-piece of its particular annunciator, two loop-plugs inserted one into a spring-jack of each line, having contact-pieces connecting with corresponding contact pieces of the spring-jacks, like contacts of the two plugs being connected by conductors, and a grounded source of electricity connected with those contact-pieces of both loop-plugs which connect with the permanently-grounded sides of the two line-circuits and of such polarity as to energize the annunciator to close together the contact-points thereupon, and a grounded source of current at each sub-station adapted to be connected with the grounded side of its line-circuit, of such polarity as to tend to actuate the annunciator to release the indicator, but of insufficient strength to effect its release, substantially as described.

In witness whereof I hereunto subscribe my name this 10th day of March, A. D. 1892.

CHARLES E. SORIBNER.

Witnesses:

M. J EANE TALLETT, GEORGE W. MCMAHON. 

